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1/*2 * DTMF decoder.3 *4 * Copyright by Andreas Eversberg (jolly@eversberg.eu)5 * based on different decoders such as ISDN4Linux6 *7 * This software may be used and distributed according to the terms8 * of the GNU General Public License, incorporated herein by reference.9 *10 */11 12#include <linux/mISDNif.h>13#include <linux/mISDNdsp.h>14#include "core.h"15#include "dsp.h"16 17#define NCOEFF 8 /* number of frequencies to be analyzed */18 19/* For DTMF recognition:20 * 2 * cos(2 * PI * k / N) precalculated for all k21 */22static u64 cos2pik[NCOEFF] =23{24 /* k << 15 (source: hfc-4s/8s documentation (www.colognechip.de)) */25 55960, 53912, 51402, 48438, 38146, 32650, 26170, 1863026};27 28/* digit matrix */29static char dtmf_matrix[4][4] =30{31 {'1', '2', '3', 'A'},32 {'4', '5', '6', 'B'},33 {'7', '8', '9', 'C'},34 {'*', '0', '#', 'D'}35};36 37/* dtmf detection using goertzel algorithm38 * init function39 */40void dsp_dtmf_goertzel_init(struct dsp *dsp)41{42 dsp->dtmf.size = 0;43 dsp->dtmf.lastwhat = '\0';44 dsp->dtmf.lastdigit = '\0';45 dsp->dtmf.count = 0;46}47 48/* check for hardware or software features49 */50void dsp_dtmf_hardware(struct dsp *dsp)51{52 int hardware = 1;53 54 if (!dsp->dtmf.enable)55 return;56 57 if (!dsp->features.hfc_dtmf)58 hardware = 0;59 60 /* check for volume change */61 if (dsp->tx_volume) {62 if (dsp_debug & DEBUG_DSP_DTMF)63 printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "64 "because tx_volume is changed\n",65 __func__, dsp->name);66 hardware = 0;67 }68 if (dsp->rx_volume) {69 if (dsp_debug & DEBUG_DSP_DTMF)70 printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "71 "because rx_volume is changed\n",72 __func__, dsp->name);73 hardware = 0;74 }75 /* check if encryption is enabled */76 if (dsp->bf_enable) {77 if (dsp_debug & DEBUG_DSP_DTMF)78 printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "79 "because encryption is enabled\n",80 __func__, dsp->name);81 hardware = 0;82 }83 /* check if pipeline exists */84 if (dsp->pipeline.inuse) {85 if (dsp_debug & DEBUG_DSP_DTMF)86 printk(KERN_DEBUG "%s dsp %s cannot do hardware DTMF, "87 "because pipeline exists.\n",88 __func__, dsp->name);89 hardware = 0;90 }91 92 dsp->dtmf.hardware = hardware;93 dsp->dtmf.software = !hardware;94}95 96 97/*************************************************************98 * calculate the coefficients of the given sample and decode *99 *************************************************************/100 101/* the given sample is decoded. if the sample is not long enough for a102 * complete frame, the decoding is finished and continued with the next103 * call of this function.104 *105 * the algorithm is very good for detection with a minimum of errors. i106 * tested it allot. it even works with very short tones (40ms). the only107 * disadvantage is, that it doesn't work good with different volumes of both108 * tones. this will happen, if accoustically coupled dialers are used.109 * it sometimes detects tones during speech, which is normal for decoders.110 * use sequences to given commands during calls.111 *112 * dtmf - points to a structure of the current dtmf state113 * spl and len - the sample114 * fmt - 0 = alaw, 1 = ulaw, 2 = coefficients from HFC DTMF hw-decoder115 */116 117u8118*dsp_dtmf_goertzel_decode(struct dsp *dsp, u8 *data, int len, int fmt)119{120 u8 what;121 int size;122 signed short *buf;123 s32 sk, sk1, sk2;124 int k, n, i;125 s32 *hfccoeff;126 s32 result[NCOEFF], tresh, treshl;127 int lowgroup, highgroup;128 s64 cos2pik_;129 130 dsp->dtmf.digits[0] = '\0';131 132 /* Note: The function will loop until the buffer has not enough samples133 * left to decode a full frame.134 */135again:136 /* convert samples */137 size = dsp->dtmf.size;138 buf = dsp->dtmf.buffer;139 switch (fmt) {140 case 0: /* alaw */141 case 1: /* ulaw */142 while (size < DSP_DTMF_NPOINTS && len) {143 buf[size++] = dsp_audio_law_to_s32[*data++];144 len--;145 }146 break;147 148 case 2: /* HFC coefficients */149 default:150 if (len < 64) {151 if (len > 0)152 printk(KERN_ERR "%s: coefficients have invalid "153 "size. (is=%d < must=%d)\n",154 __func__, len, 64);155 return dsp->dtmf.digits;156 }157 hfccoeff = (s32 *)data;158 for (k = 0; k < NCOEFF; k++) {159 sk2 = (*hfccoeff++) >> 4;160 sk = (*hfccoeff++) >> 4;161 if (sk > 32767 || sk < -32767 || sk2 > 32767162 || sk2 < -32767)163 printk(KERN_WARNING164 "DTMF-Detection overflow\n");165 /* compute |X(k)|**2 */166 result[k] =167 (sk * sk) -168 (((cos2pik[k] * sk) >> 15) * sk2) +169 (sk2 * sk2);170 }171 data += 64;172 len -= 64;173 goto coefficients;174 break;175 }176 dsp->dtmf.size = size;177 178 if (size < DSP_DTMF_NPOINTS)179 return dsp->dtmf.digits;180 181 dsp->dtmf.size = 0;182 183 /* now we have a full buffer of signed long samples - we do goertzel */184 for (k = 0; k < NCOEFF; k++) {185 sk = 0;186 sk1 = 0;187 sk2 = 0;188 buf = dsp->dtmf.buffer;189 cos2pik_ = cos2pik[k];190 for (n = 0; n < DSP_DTMF_NPOINTS; n++) {191 sk = ((cos2pik_ * sk1) >> 15) - sk2 + (*buf++);192 sk2 = sk1;193 sk1 = sk;194 }195 sk >>= 8;196 sk2 >>= 8;197 if (sk > 32767 || sk < -32767 || sk2 > 32767 || sk2 < -32767)198 printk(KERN_WARNING "DTMF-Detection overflow\n");199 /* compute |X(k)|**2 */200 result[k] =201 (sk * sk) -202 (((cos2pik[k] * sk) >> 15) * sk2) +203 (sk2 * sk2);204 }205 206 /* our (squared) coefficients have been calculated, we need to process207 * them.208 */209coefficients:210 tresh = 0;211 for (i = 0; i < NCOEFF; i++) {212 if (result[i] < 0)213 result[i] = 0;214 if (result[i] > dsp->dtmf.treshold) {215 if (result[i] > tresh)216 tresh = result[i];217 }218 }219 220 if (tresh == 0) {221 what = 0;222 goto storedigit;223 }224 225 if (dsp_debug & DEBUG_DSP_DTMFCOEFF) {226 s32 tresh_100 = tresh/100;227 228 if (tresh_100 == 0) {229 tresh_100 = 1;230 printk(KERN_DEBUG231 "tresh(%d) too small set tresh/100 to 1\n",232 tresh);233 }234 printk(KERN_DEBUG "a %3d %3d %3d %3d %3d %3d %3d %3d"235 " tr:%3d r %3d %3d %3d %3d %3d %3d %3d %3d\n",236 result[0] / 10000, result[1] / 10000, result[2] / 10000,237 result[3] / 10000, result[4] / 10000, result[5] / 10000,238 result[6] / 10000, result[7] / 10000, tresh / 10000,239 result[0] / (tresh_100), result[1] / (tresh_100),240 result[2] / (tresh_100), result[3] / (tresh_100),241 result[4] / (tresh_100), result[5] / (tresh_100),242 result[6] / (tresh_100), result[7] / (tresh_100));243 }244 245 /* calc digit (lowgroup/highgroup) */246 lowgroup = -1;247 highgroup = -1;248 treshl = tresh >> 3; /* tones which are not on, must be below 9 dB */249 tresh = tresh >> 2; /* touchtones must match within 6 dB */250 for (i = 0; i < NCOEFF; i++) {251 if (result[i] < treshl)252 continue; /* ignore */253 if (result[i] < tresh) {254 lowgroup = -1;255 highgroup = -1;256 break; /* noise in between */257 }258 /* good level found. This is allowed only one time per group */259 if (i < NCOEFF / 2) {260 /* lowgroup */261 if (lowgroup >= 0) {262 /* Bad. Another tone found. */263 lowgroup = -1;264 break;265 } else266 lowgroup = i;267 } else {268 /* higroup */269 if (highgroup >= 0) {270 /* Bad. Another tone found. */271 highgroup = -1;272 break;273 } else274 highgroup = i - (NCOEFF / 2);275 }276 }277 278 /* get digit or null */279 what = 0;280 if (lowgroup >= 0 && highgroup >= 0)281 what = dtmf_matrix[lowgroup][highgroup];282 283storedigit:284 if (what && (dsp_debug & DEBUG_DSP_DTMF))285 printk(KERN_DEBUG "DTMF what: %c\n", what);286 287 if (dsp->dtmf.lastwhat != what)288 dsp->dtmf.count = 0;289 290 /* the tone (or no tone) must remain 3 times without change */291 if (dsp->dtmf.count == 2) {292 if (dsp->dtmf.lastdigit != what) {293 dsp->dtmf.lastdigit = what;294 if (what) {295 if (dsp_debug & DEBUG_DSP_DTMF)296 printk(KERN_DEBUG "DTMF digit: %c\n",297 what);298 if ((strlen(dsp->dtmf.digits) + 1)299 < sizeof(dsp->dtmf.digits)) {300 dsp->dtmf.digits[strlen(301 dsp->dtmf.digits) + 1] = '\0';302 dsp->dtmf.digits[strlen(303 dsp->dtmf.digits)] = what;304 }305 }306 }307 } else308 dsp->dtmf.count++;309 310 dsp->dtmf.lastwhat = what;311 312 goto again;313}314